There is a growing demand for improvements in hospital settings to reduce the transmission of pathogens. This demand is driven by hospitals that have to deal with an increasing amount of cases of infections, not caused by the patient's diagnosis upon admission, but rather, due to airborne pathogens that exist in a hospital environment. These airborne pathogens pose additional health risks to patients and result in additional costs to the hospital. There are currently two approaches to reducing in-hospital transmitted contamination. The first involves decontamination of hospital room surfaces between occupancies. This can be accomplished by irradiating the room and all of its surfaces with high-level ultraviolet (UV) radiation or by spraying the room with hydrogen peroxide mist. The room must be unoccupied and isolated and if anyone wishes to enter the room during this process, significant protective equipment must be worn. Secondly, treatment of room air is an issue. A variety of units utilizing UV or HEPA type filtering or a combination of the two are currently available. There are also UV units with powerful fans that can be used to create positive or negative pressurized areas. For the area being treated, some installation of UV lighting inside ventilation ducting is also used.
Devices produced with traditional technologies have been large, difficult to locate optimally, and their performance degrades substantially with time. Currently available compact systems do not provide adequate airflow and/or pathogen kill rate. Conversely, more effective devices are currently large and difficult to maintain. Conventional UV-based systems use fluorescent tube elements. To produce adequate intensity, several tubes are often grouped together. The geometry of the tubes and their limited output per tube produces a bulky and cumbersome apparatus. The UV output of the tubes decays with time due to deterioration and with external factors such as dust settling on the tubes. Maintenance and replacement of the UV tubes is a laborious process. The size required by these units consumes critical space, which is crucial in a hospital environment. Because of their size, they cannot be located in the optimum locations to maximize their benefit. Typical units have three to four square foot cross sections and can be six feet in length and weigh about 100 pounds.
It would be desirable to have an apparatus that reduces or removes airborne pathogens, which can be used while the room is still occupied. Furthermore, it would also be desirable to have an apparatus that is portable and unobtrusive while producing a sufficiently high flow rate to be effective. Still further, it would be desirable to have an apparatus whose performance does not significantly degrade over time and is easy to maintain. Therefore, there currently exists a need in the industry for an apparatus and associated method that is compact, portable, and highly effective in reducing or removing airborne pathogens.
Currently there are a number of solutions for air purification in a hospital (or hospital-like) environment. Some of these solutions attempt to purify air by utilizing UV fluorescent tubes, but these solutions fail to meet the needs of the industry because they are large, cumbersome, and difficult to maintain. Unlike existing UV disinfection devices available on the market today, the present invention uses UV Light-Emitting Diodes (LEDs) as opposed to fluorescent tubes. LEDs are solid state devices that enjoy many advantages over fluorescent tubes. LEDs are more robust and perform better under adverse environmental conditions such as shock and vibration. LEDs do not require high voltage, so they are safer to troubleshoot and repair. They do not suffer glass breakage and their disposal does not constitute hazardous waste.
Other solutions attempt to utilize UV LEDs, but these solutions are similarly unable to meet the needs of the industry because they are unable to modulate the airflow in such a way as to provide the necessary UV radiation dosage to adequately kill the pathogens. Unlike existing solutions attempting to utilize UV LEDs, the present invention combines the irradiance field created by the UV LEDs with a modulated airflow in order to provide the necessary UV dosage to adequately kill the airborne pathogens.
The UV spectrum is divided into portions by wavelength. UVB and UVC radiation represents that portion of the spectrum that is capable of damaging biological organisms. High energy UVC photons are those with wavelengths shorter than 290 nm and are capable of traversing cellular walls. UVC radiation is used as a germicidal in order to kill airborne pathogens. UVB radiation is characterized by wavelengths between 290 and 320 nm and is also damaging to biological organisms. In order to kill pathogens, the UV radiation needs to be of a wavelength that can traverse the cellular walls. Studies have shown that the effective wavelengths for killing pathogens, such as bacteria, are in the 200 to 320 nm range. Still other studies indicate that wavelengths between 240 and 280 nm are most effective in killing a broad range of pathogens, with peak effectivity around 260 to 270 nm. The intensity or “flux” of the UV radiation is an important consideration in evaluating the effects of the UV radiation at the pathogenic level. The “UV radiation flux density” is related to the amount of radiation at the specified wavelength that reaches the surface of the pathogens. This UV radiation flux is also referred to as the “UV irradiance”. In the interaction of radiant energy with biological organisms, both wavelength and irradiance, or radiation flux, must be considered. The “UV dosage” required to effectively kill airborne pathogens is derived from a combination of UV wavelength, radiation flux, and time of exposure. The “dwell” or “residence” time is defined as the amount of time that the airborne pathogens remain exposed to the UV radiation field and are irradiated by the UV LEDs. The desired pathogen kill rate can then be optimized by properly balancing the UV LED wavelength, radiation flux, and dwell time.
Information relevant to attempts to address the problems found in the current state of the art, as described above, can be found in U.S. Pat. Nos. 6,797,044, 7,175,814, 6,053,968, 6,939,397, and 5,505,904, as well as U.S. Patent Application Nos. 20110033346, 201000132715, 20070196235, 20100260644, and 20050242013. However, each one of these references suffers from one or more of the following disadvantages: it is large or bulky; it uses fluorescent tubes; it employs a low dwell time; it achieves a low air flow rate; it does not adequately balance UV wavelength, radiation flux, and dwell time for an effective pathogen kill rate.
The present invention is unique when compared with other known devices and methods because the present invention provides: (1) a compact footprint; (2) effective pathogen removal; and (3) ease of maintenance.
The present invention is unique in that it is structurally different from other known devices or solutions. More specifically, the present invention is unique due to the presence of: (1) an air management chamber comprising a single or a plurality of reaction tubes; (2) UV LEDs embedded in the walls of the reaction tubes; and (3) specified areas of turbulent flow within the reaction tubes that increase the exposure to the UV radiation without sacrificing the air flow rate through the air management chamber.